The neurotransmitter serotonin acts on the 14 different types of serotonin receptors located at various organs and thereby incurs various physiological phenomena. Among them, the 5-HT7 receptor is the most recently cloned serotonin subtype receptor and is known to be distributed particularly at high densities in the hypothalamus, thalamus, hippocampus and cortex. Also, it is known to play important roles in thermoregulation, circadian rhythm, learning and memory, sleep, hippocampal signaling, or the like. It is also known that this receptor is involved in neurological disorders such as depression, migraine, anxiety, pain, particularly inflammatory pain and neuropathic pain, or the like.
Although there have been many efforts for development of antagonists or agonists of the 5-HT7 receptor, very few selective 5-HT7 receptor antagonists are reported. WO97/29097, WO97/49695 and WO03/048118 disclose sulfonamide-based antagonists, WO99/24022 and WO00/00472 disclose tetrahydroisoquinoline derivatives acting on the 5-HT7 receptor, and WO 2010/012817 discloses 1-aryl-4-arylmethylpiperazine derivatives acting on the 5-HT7 receptor.
However, there is still a need of a 5-HT7 receptor regulator which is selective for the 5-HT7 receptor, has a good pharmacodynamic profile, exhibits good absorption, distribution, metabolism and excretion (ADME), and is effective for neurological disorders such as depression, migraine, anxiety, pain, particularly inflammatory pain and neuropathic pain, etc. and diseases related with thermoregulation, circadian rhythm, sleep, smooth muscle, etc.